I'm not a reloader and I'm just getting my feet wet with ammunition designations, loads, primers, cases, etc., etc. I'd like to ask a simple question about .380 and 8mm. Are they the same? I've just purchased an MAS 49/56 that was refitted in the popular .308 caliber. I was told by the dealer to simply purchase milsurp 8mm to shoot in it. (BTW, the rife is in very good condition and does not have any issues with the new caliber.) The dealer indicated that shooting milsurp 8mm would ensure the primer was tough enough to avoid a slam fire scenario.

But back to my original question. Today, I purchased some milsurp 8mm ammo at a local gun show. The box ways 7.62 x 51mm Ball. The bottom of the brass says FNM 81-19. I hand fit a round into the breech and it appears to fit perfectly.

Any info any of you may want to share with me, a newbie learning caliber designation, will be greatly appreciated.

I purchased this MAS 49/56 knowing that it was originally issued as 7.5 mm. That ammo is very hard to find so, like many thousand others, this rifle was rebarreled for .308 (it says so right on the weapon, imprinted on the receiver right below the original 7.55 marking.) Now .308 caliber is 7.62 x 51 NATO which is, I believer, 8mm milsurp. The dealer said to shoot 8mm milsurp. The ammo I purchased is 7.62 x 51 ball and was sold as 8mm milsurp with the identifying marks in my original thread.

So, won't I be just fine with this ammo? I'm not shooting "modern" ammo as I want the original pressures; nothing higher.

NO! NO! NO! Where you have gone a little astray is the assumption that because someone sold you "8mm mil-surp" you actually got 8mm cartridges. 8mm DOES NOT EQUAL .308 or 7.62x51!!! 8mm is a different cartridge that is used in the 8mm Mausers that you see advertized everywhere. The 8mm is about the same size as .308 at the back end, but the case is quite a bit longer ... I don't think that it would chamber in a .308 rifle. But ... your ammo purchase is suspect and you should compare those rounds to some real 8mm and real .308 at your local sporting goods store. You want .308 or 7.62x51 nothing else!

.308 caliber is commonly called 30 caliber and was principally a US caliber. Originating way back with military rifles in the late 1800's. There are many different "chamberings" based on 30 caliber or .308" bullets.

Even though all the above chamberings fire the same .308 inch bullet, the brass case varies tremendously in size, shape, loading, pressure, etc. So a rifle chambered in 308 Winchester must be fed that EXACT type of ammunition, or very BAD things might happen.

To complicate matters the metric system is prevalent in Europe and many of their cartridges are labelled in metric measurement.

7.62 x 51 mm describes the .308 Win in millimeters rather than inches.

7.62mm = .308 inches
7.9mm = .323 inches

Slang vernacular 8mm milsurplus in general describes the 8mm mauser cartridge, which is nominally 7.9mm or .323 inches.
So, if you grabbed a 8mm mauser cartridge and put it into your 308 Win. chambered rifle and pulled the trigger.....

You are attempting to force a projectile of .323 inch diameter down a tube with a .308 inch opening. This will usually result in an explosion of your rifle, which may or may not injure/kill you.

Now whether an 8mm mauser cartridge will chamber in your 308 Win chambered rifle is another question. Sometimes the physical size of a cartridge prevents us from doing stupid things like putting the wrong round in a rifle but not always.

Hopefully I have not confused more than helped. Hopefully all the people who commented have impressed the importance of being very careful what terminology you use in describing cartridges. Using the term 8mm milsurplus is not helpful in knowing whether it will chamber and fire safely in your rifle. 8mm milsurplus likely means 8mm mauser but perhaps not always. 7.62x51 mm is just that it is not close enough to round off to 8mm<g>

I highly recommend getting and reading a reloading manual even if you never reload a round it is a wealth of info for the new shooter.

I didn't buy 8mm mauser at all so let's discount that idea. Yes, It would be very bad if I tried to stuff a large round down a narrow barrel. I now understand there is a huge difference in 8mm, .308, 7.62 based not only on the size of the round but the charge and case. But, if I've got 7.62 x 51 ammo which is a milsurp NATO round, and my rifle shoots .308 Win, which is a 7.62 x 51, then I should be ok. Right? Am I still missing something? I know there there are differences even between manufacturers. I know that Federal, for instance, produces 60,000psi while the milsurp has around 50,000 psi. The original 7.5mm round that this rifle originally shot was slightly lower. So, I'm to stay away from high pressure rounds and stick with the .308 NATO rounds. Am I finally getting it?

Now, some minor stuff: NATO ammo is designed to be used in semi-auto weapons, so they are a thousandth of an inch or so thinner in diameter. This makes for easier chambering and extracting. It is of no concern as compared to civilian ammo. It is of no concern in any bolt action rifle.

For those who reload their own ammunition, a safety item is that military cartridge cases ("brass") commonly have slightly thicker sidewalls than civilian brass. This means that if you load as much powder (civilian brass maximum-pressure load) into a military case, the pressures can be dangerously high.

Semi-auto design features for the miltary generally are uniform to operate at around 47,000 psi to 50,000 psi. Roughly. Civilian factory loadings are generally around 53,000 psi to 55,000 psi. This higher pressure can force the operating rod to cycle harder than intended, which can bend or break the rod. These pressure differences are meaningless in a bolt-action rifle, other than velocity and therefore trajectory of the bullet.

Hope this helps a bit...

Art

__________________
You're from BATFE? Come right in! I use all your fine products!

Like the farmer, you're outstanding in your field. I think I've got it now. Let me thank everyone who chimed in here. I've learned from each of you. The reason I even posted here was just to be completely sure of things before I head to the range on Tuesday. I also called a buddy who collects a lot of C&R stuff and knows quite a bit about ammo. So, he'll check everything out before we get started.

Thanks, again, every one.

Rome

PS If it is any indication of the state of the hobby, the gun show at the Eastern States Exhibition was HUGE and so was the crowd. It took me over four hours to visit all of the tables.

Difference in the exact same designation (IIRC) is that the US system measures groove depth, while the metric measures to the lands (groove is the final cut maximum diameter of the bbl while the lands are the starting/minor diameter). Obviously, the groove depth will be a larger reading. So, all things being equal, you'll have a .004" groove depth (1/2 of the diameter difference).

This only deals with the bullet itself and has absolutely nothing to do with the configuration of the case itself - whole 'nother deal.

A friend of a friend who has an MAS 49/56 in the same configuration, has just confirmed that, indeed, 7.62 x 51 milsurp ball is the same as .308 Win and this rifle had, in fact, been rebarreled to shoot it by Century Arms a number of years ago. Also, he confirms that early conversions were not done properly so there was an problem with jams primarily due to the case sticking in the breech. That, too, has been fixed and there are a number of after market options available, too.

So, I'm sorry if I've caused any confusion. I certanily do appreciate the concern, though. I realize that you can't take anything at face value and you must remind people that firearms are dangerous if misused or mishandled. That's why we have warnings on everything: to keep us vigilent to the protential threat. I never take anything for granted with my everyday firearms. It stands to reason, then, that I wouldn't ever shoot a "forign" rifle or pistol without two or three other inspections and confirmations. This is why I posted the question about the ammo, here. I've learned a lot and have lots areas to examine but it all comes with the territory.

I'll give you a range report just to confirm that I'm still here and eveything is cool. Thanks, everyone!

Rome, the only 7.62x51 converted Mas 49/56 I have seen fired at a range had a problem with slamfiring. That is, its owner loaded two rounds in the magazine (luckily only 2), squeezed the trigger, and both rounds fired. He was using CAVIM 7.62x51 ammo, because his dealer told him to use ammo with a hard primer, and the CAVIM had hard primers. I do not know the resolution of this, since this was a chance meeting at the range, and I have not seen him since. But be careful. Think twice about filling the magazine the first time, maybe load one, shoot it, then load two, and so on.

It is probably unwise to go shoot an older unfamilar rifle that has not been headspaced and safety checked. I do not know if the french gun you purchased had that done first or not. Also, in a semi auto gun there are many more moving parts and potential disasterous problems that could occur.

I dont know if the MAS 49/56 is semi-auto, bolt, lever or otherwise action. The last post would lead me to believe semi-auto. Slam fires are potentially very dangerous and could occur from any number of worn or out of spec parts.

In semi-auto military rifles the firing pins are usually free floating. This means that when the bolt strips a cartrige from the magazine and chambers it the firing pin will contact the primer lightly. Soft primers or primers seated too high may be forced forward and ignited by the firing pin floating forward. This is a "slam fire". If the the bolt has not completely made it "into battery" when this occurs------> kaboom.

The semi-auto French MAS 49/56 is the child of the sa MAS 44 and the bolt MAS 39. It was and remains an extremely accurate and reliable shooter to this day. I've added it to my growing collection of military SLR (self loading rifles) from the 1940s to the early 1960s. It is also a C&R piece.

It was a very common conversion and shoots the .308 Win ammo. My problem was trying to understand the different nomenclature and calibers. I now clearly understand the difference as pointed out by all of you in these posts. Don't worry, I won't shoot it until it's totaly checked out by a pro but it is in very excellent shape. These rifles are becoming very hard to find and I'm glad I got this one.

I know it is setup to shoot .308 Win and that't the ammo I've got for it.

I very much appreciate the concerns. Rest assured that I'm very cautious and always triple check everything before the bolt goes home.

Well, all of my initial fears have been eliminated as the MAS 49/56 I now own worked flawlessly shooting the .308 NATO ammo I purchased for it. Just thought I'd let you all know and I appreciate all of your inputs.

Just so you know, the headstamp, or markings on the head of the brass HAS NOTHING to do with the caliber of the ammunition in this case. That is a military headstamp with the FNM indicating the manfacturer, the 81-19 indicates a year and manfacturing code.
Military ammunition headstamps are all codes. Civilian headstampe USUALLY indicate the caliber.

Nothing better than a city gun shop employee who doesn't know their head from their ass when dealing with guns. Their ignorance and plain stupidity is such great entertainment. And when you, the informed shooter, walk in and ask them a question and they give you a stupid answer, it is just scary to think that they are telling good people like Rome the wrong things. I completely avoid the city type gun shops unless I want to see something before I go buy it from my local FFL friend who runs his operation as a side business. Rome stick around here and you will learn so much in so little time. I know I have. Yet I see you have over 200 posts. You already know what a resource this is.

I really feel that vast "unwashed" out there look at firearms as any other hobby and, frankly, never give the respect due to the use of firearms. Let's face it: firing a gun is an inherintly dangerous operation. You've got your hands and, in the case of rifles, face laid up against wood and steel while 50,000+ pounds of pressure created by an explosion forces a piece of lead down a barrel at supersonic speeds. Sure, these weapons are designed to work well within their tolerances but, inevitably the unanticipated happens.

That's why I'll never shoot any new weapon without having two other experienced people inspect it first and, even then, not unless I've taken the thing apart myself and inspected it. There are just too many things that can go wrong. So, El Rojo, you're right and this is why I don't mind showing my ingorance once and a while. It's also why I'll always chime in with my 2cents if I see someone willing to show theirs in this or other websites, with regard to a subject I have experience in.

Most of my 200+ posts have been questions although I've been able to contribute once and a while. I do a lot of research and read a lot about the things I'm interested in and then apply it to my experiences. But there is a never ending stream of knowledge that is available when it comes to firearms and you guys and girls help us all understand it.

Thanks for recognizing my desire to use TFL as a resource. I run in other firearms webs but this one is the very best, easiest to use, and most comprehensive. Now if we can only get a C&R forum up sometime in the near future!

One final thing about the ammo. I spoke to Bill Toth, an expert on the converted MAS rifle. He indicates that the biggest reason that my MAS fires so well is because I'm using the Portuguese ammunition as designated by the FNM on the brass. As long as I stick with that, I'm ok! (If anyone reading this is interested in how the MAS 49/56 conversion was accomplished, just ask and I'll explain what he told me.)

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